Method for reducing noise of a diesel pile hammer

ABSTRACT

A method and apparatus for reducing noise of a diesel pile hammer characterized by controlling the effective volume of a combustion chamber defined by a diesel cylinder, a ram reciprocably received in the cylinder and an anvil forming an end face of the cylinder in a manner that the combustion of the fuelair mixture is always begun just before the ram comes into contact with the anvil, regardless of the operating condition of the pile hammer, atmospheric temperature and/or pressure, the kind of fuel used, or other conditions, whereby noise due to the mechanical striking of the ram against the anvil is nullified and a substantial reduction of noise is thereby accomplished.

United States Patent 1191 UNITED STATES PATENTS 3/1930 Leonard 123/48 1) Nishimura et al. [45] F b, 5, 1974 METHOD FOR REDUCING NOISE OF A 2,054,562 9/1936 Haag 123/33 x DIESEL HAMMER 2,093,634 9/1937 Cordes 173/137 x 3,303,892 2/1967 Nishimura et al. 1. 173/!33 Inventors: shojlro Nishimura, y M8880 3,679,005 7/1972 Inaba et a]. 173/137 x Ishizaki, Kakogawa; Yoshiro Seo; Shmob both of Kobe all of Primary Examiner-Wemer H. Schroeder Japan Attorney, Agent, or Firm-Oblon, Fisher, Spivak, [73] Assignee: Kobe Steel, Ltd., Kobe, Japan Mccelland & Male! [22] F1led. Jan. 19, 1972 ABSTRACT [2]] Appl' 219008 A method and apparatus for reducing noise of a diesel pile hammer characterized by controlling the effective [30] Foreign Application Priority Data volume of a combustion chamber defined by a diesel Jan. 21, 1971 Japan 46/2045 cylinder, 8 ram reciprocahly received in the Cylinder and an anvil forming an end face of the cylinder in a 52 us. (:1 173/1, 173/134, 173/139, manner that the combustion of e fuel-air mixture is 123/33 VC 123/4 D always begun just before the ram'comes into contact [51 1m, c1 E021! 7/12 with t anvil, regardless of the operating eendttieh t [581' Field at Search 173/123, 134, 135,137, 138,- the P hammer, atmespherie temperature altd/er 173/139; 123/33 VC, 48 1) pressure, the kind of fuel used, 'or other conditions, 1 t i whereby noise due to the mechanical striking of the [56] References Cit d ram against the anvil is nullified and a substantial reduction of noise is thereby accomplished.

6 Claims, 2 Drawing Figures METHOD FOR REDUCING NOISE OF A DIESEL PILE HAMMER BACKGROUND OF THE INVENTION 1. Field Of The Invention This invention relates generally todiesel pile hammers and more particularly to a method and apparatus for reducing the characteristic noises of a diesel pile hammer.

2. Description Of The Prior Art The conventional diesel pile hammers usually make deafening noises. Therefore, when they are operated in city areas, their noise often causes serious public criticism. Various countermeasures have been employed for reducing the noises generated by diesel pile hammers, such as, for example, enclosing the body of the diesel pile hammer in a muffling cover, or mounting a muffler on the exhaust tube of the diesel cylinder. However, these countermeasures have not satisfactorily solved the problem of noise being caused by the diesel pile hammers.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a diesel pile hammer which can operate quietly enough to avoid public criticism while satisfying regulations regarding the noise levels.

Another object of this invention is to provide a method of reducing the noise characteristically generated by a diesel pile hammer in the operation of the same.

In studying the mechanics of noise generation in conventional diesel'pile hammers, it has been found that a substantial part of the noises heretofore generated by such devices is due to the direct contact of the rams thereof with their anvils, as in striking a blow.

In a diesel pile hammer, a ram which has been pushed upward by combustion gases drops in the next moment due to its gravity while compressing an amount of fresh air in a diesel cylinder. When the ram approaches the end of its downward stroke, the temperature of the compressed air reaches the natural ignition temperature of the fuel being injected into the compressed air. Then, the combustion stroke takes place, exerting a driving force on the bottom end face of the diesel cylinder or the anvil under the reaction of the ram being pushed upward by the combustion gases. In this manner of operation, it is noted that, in the conventional diesel pile hammers, the ram usually comes into direct contact with the bottom end face of the diesel cylinder in a relatively strong blow-striking manner before the ram is pushed back upward by the combustion gases, whereby a loud noise due to the mechanical pounding is generated. The noise due to the mechanical pounding is more serious in a starting period of the diesel pile hammer wherein the diesel cylinder and the ram are still cold or in the seasons of cold atmospheric temperature, because in such cases, the compressed air takes longer to attain the natural ignition temperature of the fuel, and therefore, the cushioning of the ram by the combustion gases at the lowest end of the stroke is less effective.

Based upon the aforementioned recognition of the noise generating mechanism in diesel pile hammers, the object of this invention is accomplished by constructing a diesel pile hammer in such a manner that mechanical contact of the ram with the bottom end face of the diesel cylinder or anvil is always avoided regardless of the operating condition of the pile hammer, the atmospheric temperature and/or pressure, the kind of fuel used, and the like, without sacrificing the high operating efficiency of the diesel cycle of the diesel pile hammer.

More particularly, it is proposed according to this invention that the combustion of the fuel-air mixture is begun before the ram contacts the bottom end face of the diesel cylinder or the anvil.

According to a further feature of this invention, it is proposed that the effective volume of the combustion chamber be varied according to the operating condition of the pile hammer, the atmospheric temperature a-nd/or pressure, the kind of fuel used or other conditions, to obtain the highest operating efficiency of the diesel cycle of the diesel pile hammer.

According to a particular feature of this invention, the effective volume of the combustion chamber is varied by fluidly connecting the combustion chamber with an auxiliary combustion chamber through a controlled throttling means. I

According to another particular feature of this invention, the effective volume of the combustion chamber is varied by fluidly connecting the combustion chamber with an auxiliary combustion chamber of variable volume.

BRIEF DESCRIPTION OF THE DRAWING Various other objects, features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood from the following description when considered in connection with the accompanying drawings, wherein like reference numerals designate like or corresponding parts throughout the several views, and in which:

FIG. 1 is a longitudinal sectional view of an embodiment of a diesel pile hammer constructed according to this invention; and

FIG. 2 is a similar view to that shown in FIG. 1, illustrating a second embodiment of a diesel pile hammer, constructed according to this invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring now to the drawings and more particularly to FIG. 1, a ram 1, of which only itslower essential portion is shown, is adapted to freely reciprocate vertically in a diesel cylinder 1. The lower end face of the cylinder 2 is defined by the upper end face of an anvil 3 for driving a pile P downward. A space 4 between the ram 1 and the anvil 3 in the cylinder 2 operates as the combustion chamber for the diesel cycle of the pile hammer, which is supplied with fresh air as well as exhausted of combustion gases through a port 5 according to the reciprocation of the ram 1. A fuel nozzle 6 opens into a bottom portion of the combustion chamber 4, being supplied with fuel from a fuel pump 7.

Adjacent the bottom end of the combustion chamber 4, there is provided an auxiliary combustion chamber 8, which is fluidly connected with the combustion chamber 4 through a throttle opening 9 controlled by a throttling valve 10.

The diesel pile hammer shown in FIG. 1 operates as follows:

When combustion occurs in the combustion chamber 4, the ram 1 is pushed upward by the high pressure combustion gases. When the ram'has moved so far upward as to uncover the port 5, the combustion gases are exhausted through the port to the atmosphere. As the ram 1 moves further upward due to its inertia, a vacuum is generated in the combustion chamber 4,

' whereby fresh air is drawn into the combustion chamber through the port 5. In the subsequent downward stroke of the ram 1, the port 5 is first covered by the ram, and thereafter compression of the air contained in the combustion chamber 4 is effected. As the compression of the air in the combustion chamber 4 proceeds according to the downward movement of the ram 1, the temperature of the air rises and here it is so adapted that the temperature exceeds the natural ignition temperature of the fuel before the ram 1 reaches the lowermost position in the cylinder 2. In synchronization with the reciprocating movement of the ram 1, the fuel pump-7 is operated to inject a predetermined amount of fuel from the nozzle 6 into the combustion chamber 4. Then combustion takes place and the ram 1 is again pushed upward while supporting the reaction of the combustion force being applied to the anvil 3.

In the starting period of the pile hammer, wherein the ram 1, the cylinder 2 and the anvil 3 are still cold, the valve is tightened to isolate the auxiliary combustion chamber 8 from the combustion chamber 4, whereby theeffective volume of the combustion chamber is reduced to the primary combustion chamber 4. In this reduced volume of the combustion chamber, the air is compressed with a higher ratio than in the larger volume ofthe combustion chamber which can be obtained by opening the combustion chamber 4 to the auxiliary combustion chamber 8 through a loosened throttle opening 9. Therefore, an air temperature which is high enough to cause natural ignition of fuel is obtained before the ram 1 reaches the lowermost position of the downward stroke even when the combustion chamber is surrounded by relatively cold walls. Thus, the ram 1 may be prevented from coming into contact with the anvil 3 such that it would generate a loud noise due to the mechanical contact therebetween.

After a period of warming-up operation, the temperature of the ram, cylinderv and anvil reaches a normal operating temperature. Then, the valve 10 is loosened to properly increase the effective volume of the combustion chamber so that the stroke of the ram is elongated to its maximum extent without coming into direct contact with the anvil, to obtain the highest efficiency of the diesel cycle. Since, in this condition, the air is confined in relatively hot walls defining the combustion chamber, the air reaches the natural ignition temperature of fuel with a lower compression ratio than ever.

operating condition as sometimes occurs in the convenfective volume of the combustion chamber to lower the compression ratio of the air when any overheating is observed.

FIG. 2 shows another embodiment of the diesel pile hammer according to this invention, wherein the effective volume of the combustion chamber is varied by changing the effective volume of the auxiliary combustion chamber 8, the latter volume being changed by displacing a piston l 1 along the cylindrical wall of the auxiliary combustion chamber 8.

It will be apparent that the diesel pile hammer shown in FIG. 2 operates exactly in the same manner as that shown in FIG. 1.

Obviously many other variations and modifications of the present invention are possible in light of these teachings. It is to be understood, therefore, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. Accordingly,

What is claimed as new and desired to be secured by letters patent of the United States is:

l. A method for continuously reducing hammering noise throughout the repeated operation of a diesel pile tional diesel pile hammers, is avoided in this case. Such damages are prevented by properly increasing the efhammer which is provided with a diesel cylinder providing a main combustion chamber, a ram reciprocably mounted in the cylinder and an anvil at one end of the cylinder normally adapted to be struck by said ram upon descent thereof, comprising the steps of:

introducing combustible fuel into said main combustion chamber during each descent of said ram toward said anvil, providing an auxiliary combustion chamber in communication with said main combustion chamber through an adjustable throttling valve, continuously throttling the degree of effective communication between said main combustion chamber and said auxiliary combustion chamber during repeated descent of said ram toward said anvil, thereby continuously varying the combined volume of said main combustion chamber and of said auxiliary combustion chamber throughout the repeated operation of said diesel pile hammer, repeatedly descending said ram within said cylinder to create the pressure at which combustion of said fuel occurs within the varied combined volume of said main and said auxiliary combustion chambers, and continuously limiting the repeated stroke of said ram to stop short of said anvil during repeated descent of said ram toward said'anvil by continuously varying said combined volume of said main and said auxiliary cylinders which is necessary to support the pressure at which combustion of said fuel occurs before said ram strikes said anvil, thereby continuously preventing contact of said ram with said anvil throughout the repeated operation of said diesel hammer.

2. The method as recited in claim 1, wherein said throttling valve comprises a variable size opening between said auxiliary and said main combustion chambers, and further including the step of: continuously varying the size of said opening to continuously adjust said throttling means during repeated descent of said ram.

3. The method as recited in claim 1, wherein said throttling valve comprises a piston slidably displaceable within said auxiliary combustion chamber for varying the volume of said auxiliary combustion chamber, and further including the step-of:

continuously adjusting the position of said piston slidably within said auxiliary combustion chamber to vary the volume of said auxiliary combustion chamber and thereby vary the degree of effective communication of said main combustion chamber with said auxiliary combustion chamber. 4. The method as recited in claim 1, and further including the steps of:

communicating a fuel injector with said main combustion chamber at a location remote from said auxiliary combustion chamber, and injecting fuel with said fuel injector directly into said main combustion chamber without injecting said fuel also into said auxiliary combustion chamber. 5. The method as recited in claim 1, and further including the steps of:

closing said throttling valve to prevent communication of said auxiliary combustion chamber with said main combustion chamber during initial descent of said ram toward said anvil, and creating combustion in said main combustion chamber before said ram contacts said anvil during the initial descent of said ram toward said anvil. 6. A method for reducing noise in a diesel pile hammer having a diesel cylinder, a ram reciprocably received in said cylinder, and an anvil forming an end of said cylinder and normally adapted to be struck by the ram upon descent thereof, comprising the steps of:

creating combustion in said cylinder during each descent of said ram and before said ram descends into contact with said anvil, varying the effective volume of a combustion chamber defined in said cylinder between said ram and said anvil to maintain a pressure in said cylinder sufficient to support combustion of fuel during each descent of said ram, varying the effective volume of said combustion chamber defined in said cylinder between said ram and said anvil to maintain sufficient volume of air necessary to support the air pressure at which the natural ignition temperature of fuel within the cylinder occurs before said ram descends into contact with said anvil, and continuously throttling the degree of communication between said combustion chamber and an auxiliary combustion chamber communicating with said cylinder in order to vary the effective volume of the combustion chamber defined in said cylinder. 

1. A method for continuously reducing hammering noise throughout the repeated operation of a diesel pile hammer which is provided with a diesel cylinder providing a main combustion chamber, a ram reciprocably mounted in the cylinder and an anvil at one end of the cylinder normally adapted to be struck by said ram upon descent thereof, comprising the steps of: introducing combustible fuel into said main combustion chamber during each descent of said ram toward said anvil, providing an auxiliary combustion chamber in communication with said main combustion chamber through an adjustable throttling valve, continuously throttling the degree of effective communication between said main combustion chamber and said auxiliary combustion chamber during repeated descent of said ram toward said anvil, thereby continuously varying the combined volume of said main combustion chamber and of said auxiliary combustion chamber throughout the repeated operation of said diesel pile hammer, repeatedly descending said ram within said cylinder to create the pressure at which combustion of said fuel occurs within the varied combined volume of said main and said auxiliary combustion chambers, and continuously limiting the repeated stroke of said ram to stop short of said anvil during repeated descent of said ram toward said anvil by continuously varying said combined volume of said main and said auxiliary cylinders which is necessary to support the pressure at which combustion of said fuel occurs before said ram strikes said anvil, thereby continuously preventing contact of said ram with said anvil throughout the repeated operation of said diesel hammer.
 2. The method as recited in claim 1, wherein said throttling valve comprises a variable size opening between said auxiliary and said main combustion chambers, and further including the step of: continuously varying the size of said opening to continuously adjust said throttling means during repeated descent of said ram.
 3. The method as recited in claim 1, wherein said throttling valve comprises a piston slidably displaceable within said auxiliary combustion chamber for varying the volume of said auxiliary combustion chamber, and further including the step of: continuously adjusting the position of said piston slidably within said auxiliary combustion chamber to vary the volume of said auxiliary combustion chamber and thereby vary the degree of effective communication of said main combustion chamber with said auxiliary combustion chamber.
 4. The method as recited in claim 1, and further including the steps of: communicating a fuel injector with said main combustion chamber at a location remote from said auxiliary combustion chamber, and injecting fuel with said fuel injector directly into said main combustion chamber without injecting said fuel also into said auxiliary combustion chamber.
 5. The method as recited in claim 1, and further including the steps of: closing said throttling valve to prevent communication of said auxiliary combustion chamber with said main combustion chamber during initial descent of said ram toward said anvil, and creating combustion in said main combustion chamber before said ram contacts said anvil during the initial descent of said ram toward said anvil.
 6. A method for reducing noise in a diesel pile hammer having a diesel cylinder, a ram reciprocably received in said cylinder, and an anvil forming an end of said cylinder and normally adapted to be struck by the ram upon descent thereof, comprising the steps of: creating combustion in said cylinder during each descent of said ram and before said ram descends into contact with said anvil, varying the effective volume of a combustion chamber defined in said cylinder between said ram and said anvil to maintain a pressure in said cylinder sufficient to support combustion of fuel during each descenT of said ram, varying the effective volume of said combustion chamber defined in said cylinder between said ram and said anvil to maintain sufficient volume of air necessary to support the air pressure at which the natural ignition temperature of fuel within the cylinder occurs before said ram descends into contact with said anvil, and continuously throttling the degree of communication between said combustion chamber and an auxiliary combustion chamber communicating with said cylinder in order to vary the effective volume of the combustion chamber defined in said cylinder. 